scholarly journals Tracking the genome of four Pseudomonas aeruginosa isolates that have a defective Las quorum-sensing system, but are still virulent

2020 ◽  
Vol 2 (7) ◽  
Author(s):  
Enrique Martínez-Carranza ◽  
Selene García-Reyes ◽  
Abigail González-Valdez ◽  
Gloria Soberón-Chávez
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Type Species ◽  
Water System ◽  
Clinical Strain ◽  
Content Type ◽  
Sensing System ◽  
Link Type ◽  
The Indian Ocean ◽  
Type Strains

In this work we analysed the whole genome extended multilocus sequence typing (wgMLST) of four Pseudomonas aeruginosa strains that are characterized by being virulent despite having a defective Las quorum-sensing (QS) system, and compare them with the wgMLST of the PAO1 and PA14 type strains. This comparison was done to determine whether there was a genomic characteristic that was common to the strains with an atypical QS response. The analysed strains include two environmental isolates (ID 4365 isolated from the Indian Ocean, and M66 isolated from the Churince water system in Cuatro Ciénegas Coahuila, México), one veterinary isolate (strain 148 isolated from the stomach of a dolphin) and a clinical strain (INP43 that is a cystic fibrosis pediatric isolate). We determine that the six analysed strains have a core genome of 4689 loci that was used to construct a wgMLST-phylogeny tree. Using the cano-wgMLST_BacCompare software we found that there was no common genomic characteristic to the strains with an atypical QS-response and we identify ten loci that are highly discriminatory of the six strains’ phylogeny so that their MLST can reconstruct the wgMLST-phylogeny tree of these strains. We discuss here the nature of these ten highly discriminatory genes in the context of P. aeruginosa virulence and evolution.

scholarly journals Study of quorum-sensing LasR and RhlR genes and their dependent virulence factors in Pseudomonas aeruginosa isolates from infected burn wounds

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Aya Ahmad Elnegery ◽  
Wafaa Kamel Mowafy ◽  
Tarek Ahmed Zahra ◽  
Noha Tharwat Abou El-Khier
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Proteolytic Activity ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Type Species ◽  
Assay Method ◽  
Content Type ◽  
Burn Wounds ◽  
Link Type

Background. Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen responsible for burn-wound infection. High incidence, infection severity and increasing resistance characterize P. aeruginosa -induced burn infection. Purpose. To estimate quorum-sensing (QS)-dependent virulence factors of P. aeruginosa isolates from burn wounds and correlate it to the presence of QS genes. Methods. A cross-sectional descriptive study included 50 P . aeruginosa isolates from burn patients in Mansoura University Plastic and Burn Hospital, Egypt. Antibiotic sensitivity tests were done. All isolates were tested for their ability to produce biofilm using a micro-titration assay method. Protease, pyocyanin and rhamnolipid virulence factors were determined using skimmed milk agar, King’s A medium and CTAB agar test, respectively. The identity of QS lasR and rhlR genes was confirmed using PCR. Results. In total, 86 % of isolates had proteolytic activity. Production of pyocyanin pigment was manifested in 66 % of isolates. Altogether, 76 % of isolates were rhamnolipid producers. Biofilm formation was detected in 96 % of isolates. QS lasR and rhlR genes were harboured by nearly all isolates except three isolates were negative for both lasR and rhlR genes and two isolates were positive for lasR gene and negative for rhlR gene. Forty-nine isolates were considered as extremely QS-proficient strains as they produced QS-dependent virulence factors. In contrast, one isolate was a QS deficient strain. Conclusions. QS affects P. aeruginosa virulence-factor production and biofilm in burn wounds. Isolates containing lasR and rhlR seem to be a crucial regulator of virulence factors and biofilm formation in P. aeruginosa whereas the lasR gene positively regulates biofilm formation, proteolytic activity, pyocyanin production and rhamnolipid biosurfactant synthesis. The QS regulatory RhlR gene affects protease and rhamnolipid production positively.

scholarly journals Combinatorial quorum sensing in Pseudomonas aeruginosa allows for novel cheating strategies

Microbiology ◽  
2020 ◽  
Vol 166 (8) ◽  
pp. 777-784 ◽  
Author(s):  
James Gurney ◽  
Sheyda Azimi ◽  
Sam P. Brown ◽  
Stephen P. Diggle
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Type Species ◽  
Natural Populations ◽  
Opportunistic Pathogen ◽  
Growth Media ◽  
Public And Private ◽  
Content Type ◽  
Private Goods ◽  
Link Type

In the opportunistic pathogen Pseudomonas aeruginosa, quorum sensing (QS) is a social trait that is exploitable by non-cooperating cheats. Previously it has been shown that by linking QS to the production of both public and private goods, cheats can be prevented from invading populations of cooperators and this was described by Dandekar et al. (Science 2012;338:264–266) as ‘a metabolic incentive to cooperate’. We hypothesized that P. aeruginosa could evolve novel cheating strategies to circumvent private goods metabolism by rewiring its combinatorial response to two QS signals (3O-C12-HSL and C4-HSL). We performed a selection experiment that cycled P. aeruginosa between public and private goods growth media and evolved an isolate that rewired its control of cooperative protease expression from a synergistic (AND-gate) response to dual-signal input to a 3O-C12-HSL-only response. We show that this isolate circumvents metabolic incentives to cooperate and acts as a combinatorial signalling cheat, with higher fitness in competition with its ancestor. Our results show three important principles: first, combinatorial QS allows for diverse social strategies to emerge; second, restrictions levied by private goods are not sufficient to explain the maintenance of cooperation in natural populations; and third, modifying combinatorial QS responses could result in important physiological outcomes in bacterial populations.

2-Alkyl-4-quinolone quorum sensing molecules are biomarkers for culture-independent Pseudomonas aeruginosa burden in adults with cystic fibrosis

2021 ◽  
Vol 70 (10) ◽  
Author(s):  
Nur Masirah M. Zain ◽  
Karmel Webb ◽  
Iain Stewart ◽  
Nigel Halliday ◽  
David A. Barrett ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Type Species ◽  
Bacterial Load ◽  
Pulmonary Exacerbation ◽  
Content Type ◽  
Link Type ◽  
Culture Independent ◽  
Clinical Stability

Introduction. Pseudomonas aeruginosa produces quorum sensing signalling molecules including 2-alkyl-4-quinolones (AQs), which regulate virulence factor production in the cystic fibrosis (CF) airways. Hypothesis/Gap statement. Culture can lead to condition-dependent artefacts which may limit the potential insights and applications of AQs as minimally-invasive biomarkers of bacterial load. Aim. We aimed to use culture-independent methods to explore the correlations between AQ levels and live P. aeruginosa load in adults with CF. Methodology. Seventy-five sputum samples at clinical stability and 48 paired sputum samples obtained at the beginning and end of IV antibiotics for a pulmonary exacerbation in adults with CF were processed using a viable cell separation technique followed by quantitative P. aeruginosa polymerase chain reaction (qPCR). Live P. aeruginosa qPCR load was compared with the concentrations of three AQs (HHQ, NHQ and HQNO) detected in sputum, plasma and urine. Results. At clinical stability and the beginning of IV antibiotics for pulmonary exacerbation, HHQ, NHQ and HQNO measured in sputum, plasma and urine were consistently positively correlated with live P. aeruginosa qPCR load in sputum, compared to culture. Following systemic antibiotics live P. aeruginosa qPCR load decreased significantly (P<0.001) and was correlated with a reduction in plasma NHQ (plasma: r=0.463, P=0.003). Conclusion. In adults with CF, AQ concentrations correlated more strongly with live P. aeruginosa bacterial load measured by qPCR compared to traditional culture. Prospective studies are required to assess the potential of systemic AQs as biomarkers of P. aeruginosa bacterial burden.

scholarly journals Role of quorum sensing in UVA-induced biofilm formation in Pseudomonas aeruginosa

Microbiology ◽  
2020 ◽  
Vol 166 (8) ◽  
pp. 735-750 ◽  
Author(s):  
Magdalena Pezzoni ◽  
Ramón A. Pizarro ◽  
Cristina S. Costa
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Type Species ◽  
Transcriptional Level ◽  
Content Type ◽  
Link Type ◽  
Opportunistic Human Pathogen ◽  
Biofilm Development

Pseudomonas aeruginosa , a versatile bacterium present in terrestrial and aquatic environments and a relevant opportunistic human pathogen, is largely known for the production of robust biofilms. The unique properties of these structures complicate biofilm eradication, because they make the biofilms very resistant to diverse antibacterial agents. Biofilm development and establishment is a complex process regulated by multiple regulatory genetic systems, among them is quorum sensing (QS), a mechanism employed by bacteria to regulate gene transcription in response to population density. In addition, environmental factors such as UVA radiation (400–315 nm) have been linked to biofilm formation. In this work, we further investigate the mechanism underlying the induction of biofilm formation by UVA, analysing the role of QS in this phenomenon. We demonstrate that UVA induces key genes of the Las and Rhl QS systems at the transcriptional level. We also report that pelA and pslA genes, which are essential for biofilm formation and whose transcription depends in part on QS, are significantly induced under UVA exposure. Finally, the results demonstrate that in a relA strain (impaired for ppGpp production), the UVA treatment does not induce biofilm formation or QS genes, suggesting that the increase of biofilm formation due to exposure to UVA in P. aeruginosa could rely on a ppGpp-dependent QS induction.

Catenulispora graminis sp. nov., a rhizobacterium from bamboo (Phyllostachys nigro var. henonis) rhizosphere soil

2012 ◽  
Vol 62 (Pt_11) ◽  
pp. 2589-2592 ◽  
Author(s):  
Hyo-Jin Lee ◽  
Song-Ih Han ◽  
Kyung-Sook Whang
Keyword(s):  
Type Species ◽  
Rhizosphere Soil ◽  
Major Fatty Acid ◽  
Rrna Gene ◽  
Phenotypic Data ◽  
Content Type ◽  
Dna Relatedness ◽  
Link Type ◽  
Isoprenoid Quinones ◽  
Type Strains

A novel actinobacterium, designated strain BR-34T, was isolated from rhizosphere soil of bamboo (Phyllostachys nigro var. henonis) sampled in Damyang, Korea. The strain was found to have morphological and chemotaxonomic characteristics typical of the genus Catenulispora . The strain contained iso-C16 : 0 as the major fatty acid and MK-9(H4), MK-9(H6) and MK-9(H8) as major isoprenoid quinones. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain BR-34T formed a cluster separate from members of the genus Catenulispora and was related most closely to Catenulispora acidiphila ID139908T (97.4 % similarity), Catenulispora rubra Aac-30T (97.3 %), Catenulispora yoronensis TT N02-20T (97.3 %) and Catenulispora subtropica TT 99-48T (97 %). However, the level of DNA–DNA relatedness between strain BR-34T and C. acidiphila ID139908T was only 45.32 %. Based on DNA–DNA relatedness, morphological and phenotypic data, strain BR-34T could be distinguished from the type strains of phylogenetically related species. It is therefore considered to represent a novel species of the genus Catenulispora , for which the name Catenulispora graminis sp. nov. is proposed. The type strain is BR-34T ( = KACC 15070T = NBRC 107755T).

Flavobacterium akiainvivens sp. nov., from decaying wood of Wikstroemia oahuensis, Hawai‘i, and emended description of the genus Flavobacterium

2013 ◽  
Vol 63 (Pt_9) ◽  
pp. 3280-3286 ◽  
Author(s):  
Iris Kuo ◽  
Jimmy Saw ◽  
Durrell D. Kapan ◽  
Stephanie Christensen ◽  
Kenneth Y. Kaneshiro ◽  
...  
Keyword(s):  
Type Species ◽  
Original Description ◽  
Gliding Motility ◽  
Rrna Gene ◽  
Content Type ◽  
Phenotypic Differences ◽  
Whole Cells ◽  
Link Type ◽  
Decaying Wood ◽  
Type Strains

Strain IK-1T was isolated from decaying tissues of the shrub Wikstroemia oahuensis collected on O‘ahu, Hawai‘i. Cells were rods that stained Gram-negative. Gliding motility was not observed. The strain was oxidase-negative and catalase-positive. Zeaxanthin was the major carotenoid. Flexirubin-type pigments were not detected. The most abundant fatty acids in whole cells of IK-1T grown on R2A were iso-C15 : 0 and one or both of C16 : 1ω7c and C16 : 1ω6c. Based on comparisons of the nucleotide sequence of the 16S rRNA gene, the closest neighbouring type strains were Flavobacterium rivuli WB 3.3-2T and Flavobacterium subsaxonicum WB 4.1-42T, with which IK-1T shares 93.84 and 93.67 % identity, respectively. The G+C content of the genomic DNA was 44.2 mol%. On the basis of distance from its nearest phylogenetic neighbours and phenotypic differences, the species Flavobacterium akiainvivens sp. nov. is proposed to accommodate strain IK-1T ( = ATCC BAA-2412T = CIP 110358T) as the type strain. The description of the genus Flavobacterium is emended to reflect the DNA G+C contents of Flavobacterium akiainvivens IK-1T and other species of the genus Flavobacterium described since the original description of the genus.

scholarly journals Burkholderia insulsa sp. nov., a facultatively chemolithotrophic bacterium isolated from an arsenic-rich shallow marine hydrothermal system

2015 ◽  
Vol 65 (Pt_1) ◽  
pp. 189-194 ◽  
Author(s):  
Antje Rusch ◽  
Shaer Islam ◽  
Pratixa Savalia ◽  
Jan P. Amend
Keyword(s):  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
The Novel ◽  
Carbohydrate Utilization ◽  
Content Type ◽  
Link Type ◽  
Optimum Ph ◽  
Shallow Marine Hydrothermal System ◽  
Type Strains

Enrichment cultures inoculated with hydrothermally influenced nearshore sediment from Papua New Guinea led to the isolation of an arsenic-tolerant, acidophilic, facultatively aerobic bacterial strain designated PNG-AprilT. Cells of this strain were Gram-stain-negative, rod-shaped, motile and did not form spores. Strain PNG-AprilT grew at temperatures between 4 °C and 40 °C (optimum 30–37 °C), at pH 3.5 to 8.3 (optimum pH 5–6) and in the presence of up to 2.7 % NaCl (optimum 0–1.0 %). Both arsenate and arsenite were tolerated up to concentrations of at least 0.5 mM. Metabolism in strain PNG-AprilT was strictly respiratory. Heterotrophic growth occurred with O2 or nitrate as electron acceptors, and aerobic lithoautotrophic growth was observed with thiosulfate or nitrite as electron donors. The novel isolate was capable of N2-fixation. The respiratory quinones were Q-8 and Q-7. Phylogenetically, strain PNG-AprilT belongs to the genus Burkholderia and shares the highest 16S rRNA gene sequence similarity with the type strains of Burkholderia fungorum (99.8 %), Burkholderia phytofirmans (98.8 %), Burkholderia caledonica (98.4 %) and Burkholderia sediminicola (98.4 %). Differences from these related species in several physiological characteristics (lipid composition, carbohydrate utilization, enzyme profiles) and DNA–DNA hybridization suggested the isolate represents a novel species of the genus Burkholderia , for which we propose the name Burkholderia insulsa sp. nov. The type strain is PNG-AprilT ( = DSM 28142T = LMG 28183T).

Reclassification of Parvularcula flava as Aquisalinus luteolus nom. nov. and emended description of the genus Aquisalinus

2021 ◽  
Vol 71 (10) ◽  
Author(s):  
Jun-Jie Ying ◽  
Zhi-Cheng Wu ◽  
Yuan-Chun Fang ◽  
Lin Xu ◽  
Cong Sun
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Gene Sequences ◽  
16S Rrna Gene Sequences ◽  
Content Type ◽  
Link Type ◽  
Type Strains

Parvularcula flava was proposed as a novel member of genus Parvularcula in 2016. Some time earlier, Aquisalinus flavus has been proposed as a novel species of a novel genus named Aquisalinus . When comparing the 16S rRNA gene sequences of type strains P. flava NH6-79T and A. flavus D11M-2T, they showed 97.9 % sequence identity, much higher than the sequence identities 92.7–94.3 % between P. flava NH6-79T and type strains in the genus Parvularcula , indicating that the later proposed novel taxon Parvularcula flava need reclassification. The phylogenetic trees based on 16S rRNA gene sequences and genome sequences both showed that P. flava NH6-79T and A. flavus D11M-2T formed a separated branch away from strains in the genera Parvularcula , Marinicaulis and Amphiplicatus . The average amino acid identity and average nucleotide identity values of P. flava NH6-79T and A. flavus D11M-2T were 87.9 and 85.0 %, respectively, much higher than the values between P. flava NH6-79T and other closely related type strains (54.3 %–58.1 % and 68.6–70.4 %, respectively). P. flava NH6-79T and A. flavus D11M-2T also contained summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c) and C16 : 0 as major fatty acids, distinguishing them from other closely related taxa. Based on the results of the phylogenetic, comparative genomic and phenotypic analyses, Parvularcula flava should be reclassified as Aquisalinus luteolus nom. nov. and the description of genus Aquisalinus is emended.

Rhizobium changzhiense sp. nov., isolated from effective nodules of Vicia sativa L. in North China

2021 ◽  
Author(s):  
Junjie Zhang ◽  
Shanshan Peng ◽  
Mitchell Andrews ◽  
Chunzeng Liu ◽  
Yimin Shang ◽  
...  
Keyword(s):  
Type Species ◽  
Rrna Gene ◽  
Vicia Sativa ◽  
Common Vetch ◽  
Content Type ◽  
Link Type ◽  
Gene Sequence Analysis ◽  
Rhizobial Species ◽  
Distinct Lineage ◽  
Type Strains

Three fast-growing rhizobial strains isolated from effective nodules of common vetch (Vicia sativa L.) were characterized using a polyphasic approach. All three strains were assigned to the genus Rhizobium on the basis of the results of 16S rRNA gene sequence analysis. Phylogenetic analysis based on concatenated atpD-recA genes separated the strains into a distinct lineage represented by WYCCWR 11279T, which showed average nucleotide identity values of 95.40 and 93.61 % with the most similar phylogenetic type strains of Rhizobium sophorae CCBAU 03386T and Rhizobium laguerreae FB TT, respectively. The digital DNA–DNA hybridization relatedness values between WYCCWR 11279T and the closest related type strains were less than 70 %. Therefore, a novel rhizobial species is proposed, Rhizobium changzhiense sp. nov., and strain WYCCWR 11279T (=HAMBI 3709T=LMG 31534T) is designated as the type strain for the novel species.

Novosphingobium decolorationis sp. nov., an aniline blue-decolourizing bacterium isolated from East Pacific sediment

2021 ◽  
Vol 71 (9) ◽  
Author(s):  
Xiunuan Chen ◽  
Bingxia Dong ◽  
Ting Chen ◽  
Na Ren ◽  
Jing Wang ◽  
...  
Keyword(s):  
Type Species ◽  
Phylogenetic Analyses ◽  
Cellular Fatty Acid ◽  
Aniline Blue ◽  
Rrna Gene ◽  
Polar Lipid Profile ◽  
Content Type ◽  
Link Type ◽  
East Pacific ◽  
Type Strains

Aniline blue-decolourizing bacterial strain 502str22T, isolated from sediment collected in the East Pacific, was subjected to characterization by a polyphasic taxonomic approach. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain 502str22T belongs to the genus Novosphingobium , with closely related type strains ‘ Novosphingobium profundi ’ F72T (97.6%), N. mathurense SM117T (97.1%) and N. arvoryzae Jyi-02T (97.0%). Digital DNA–DNA hybridization and average nucleotide identity values between strain 502str22T and closely related type strains were 20.3–24.8% and 74.1–81.9%, respectively. The major cellular fatty acid (>10%) was C18:1 ω7c. The polar lipid profile consisted of a mixture of phosphatidylcholine, one sphingoglycolipid, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylmonomethylethanolamine. The DNA G+C content of strain 502str22T was 65.5 mol%. The polyphasic taxonomic results indicated that strain 502str22T represents a novel species of the genus Novosphingobium , for which the name Novosphingobium decolorationis sp. nov is proposed. The type strain is 502str22T (=KCTC 82134T= MCCC 1K04799 T).

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